Automated filter testers for testing filters, respirator cartridges and filter media have been previously developed. One such automated filter tester is the CERTITEST® filter tester manufactured by TSI incorporated. According to TSI, the CERTITEST® Models 8127 and 8130 are automated filter testers designed to test filters, respirator cartridges and filter media. Model 8127 uses an oil aerosol while Model 8130 uses either an oil aerosol or a salt aerosol. The Model 8127 and 8130 monitor filter penetration and resistance over a range of filter flows. Models 8127 and 8130 have significant limitations. Specifically, the aerosol generator in each of Models 8127 and 8130 must be manually replenished with liquid used to create the test aerosol. This requires that the liquid level in the aerosol generator be monitored. Further, the filter tester must be shutdown while the liquid in the aerosol generator is replenished, i.e., the filter tester cannot be used to test filters or any other device while the liquid supply for the aerosol generator is being replenished. Another limitation on Models 8127 and 8130 concerns the drip jar or collector that is associated with the impactor. More specifically, once a pressurized gas is introduced in the liquid solution (either oil or salt) in the aerosol generator, the test aerosol is created. The test aerosol is subjected to an impactor to refine the test aerosol in an effort to provide an optimum test aerosol to challenge the object to be tested. A drip jar is associated with the impactor to collect liquid particles descending downwardly after the test aerosol strikes the impactor. The drip jar or collector must be frequently emptied. Once again, the filter tester cannot be used to test filters or any other device while the drip jar or collector is being emptied. Models 8127 and 8130 also require a separate mixing chamber downstream of the aerosol generator for mixing the test aerosol with heated dilution air downstream of the aerosol generator.
Other automated filter testers include the TDA-100 series testers manufactured by Air Techniques International, a division of Hamilton Associates, Inc. The TDA-100 series testers use a salt aerosol and an oil aerosol depending upon the model to challenge a test object. The liquid reservoir of the aerosol is visible from the exterior of the cabinet housing through a window. The reservoir of the aerosol generator includes a pair of lines that indicate the maximum and minimum levels of liquid (i.e., oil solution or salt solution) to be maintained in the reservoir. Accordingly, the operator must continuously monitor the liquid level of the reservoir. When the liquid needs to be replenished, the pressurized gas normally used to create the test aerosol is diverted to a supply reservoir to direct a liquid to the reservoir of the aerosol generator to maintain the proper liquid level in the reservoir of the aerosol generator. While the refilling process is initiated by an operator pressing an external button on the test unit, the operator must continuously monitor the liquid level while the reservoir of the aerosol generator is being refilled or replenished with liquid. The TDA-100 series testers cannot test any objects while the reservoir of the aerosol is being refilled. In addition, the operator must monitor the aerosol generator reservoir during filtering to determine when to refill the reservoir.